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revision 92 by nigel, Sat Feb 24 21:41:34 2007 UTC revision 93 by nigel, Sat Feb 24 21:41:42 2007 UTC
# Line 32  man page, in case the conversion went wr Line 32  man page, in case the conversion went wr
32  <li><a name="TOC17" href="#SEC17">DUPLICATE SUBPATTERN NAMES</a>  <li><a name="TOC17" href="#SEC17">DUPLICATE SUBPATTERN NAMES</a>
33  <li><a name="TOC18" href="#SEC18">FINDING ALL POSSIBLE MATCHES</a>  <li><a name="TOC18" href="#SEC18">FINDING ALL POSSIBLE MATCHES</a>
34  <li><a name="TOC19" href="#SEC19">MATCHING A PATTERN: THE ALTERNATIVE FUNCTION</a>  <li><a name="TOC19" href="#SEC19">MATCHING A PATTERN: THE ALTERNATIVE FUNCTION</a>
35    <li><a name="TOC20" href="#SEC20">SEE ALSO</a>
36  </ul>  </ul>
37  <br><a name="SEC1" href="#TOC1">PCRE NATIVE API</a><br>  <br><a name="SEC1" href="#TOC1">PCRE NATIVE API</a><br>
38  <P>  <P>
# Line 140  man page, in case the conversion went wr Line 141  man page, in case the conversion went wr
141  </P>  </P>
142  <br><a name="SEC2" href="#TOC1">PCRE API OVERVIEW</a><br>  <br><a name="SEC2" href="#TOC1">PCRE API OVERVIEW</a><br>
143  <P>  <P>
144  PCRE has its own native API, which is described in this document. There is  PCRE has its own native API, which is described in this document. There are
145  also a set of wrapper functions that correspond to the POSIX regular expression  also some wrapper functions that correspond to the POSIX regular expression
146  API. These are described in the  API. These are described in the
147  <a href="pcreposix.html"><b>pcreposix</b></a>  <a href="pcreposix.html"><b>pcreposix</b></a>
148  documentation. Both of these APIs define a set of C function calls. A C++  documentation. Both of these APIs define a set of C function calls. A C++
# Line 170  documentation describes how to run it. Line 171  documentation describes how to run it.
171  A second matching function, <b>pcre_dfa_exec()</b>, which is not  A second matching function, <b>pcre_dfa_exec()</b>, which is not
172  Perl-compatible, is also provided. This uses a different algorithm for the  Perl-compatible, is also provided. This uses a different algorithm for the
173  matching. The alternative algorithm finds all possible matches (at a given  matching. The alternative algorithm finds all possible matches (at a given
174  point in the subject). However, this algorithm does not return captured  point in the subject), and scans the subject just once. However, this algorithm
175  substrings. A description of the two matching algorithms and their advantages  does not return captured substrings. A description of the two matching
176  and disadvantages is given in the  algorithms and their advantages and disadvantages is given in the
177  <a href="pcrematching.html"><b>pcrematching</b></a>  <a href="pcrematching.html"><b>pcrematching</b></a>
178  documentation.  documentation.
179  </P>  </P>
# Line 243  documentation. Line 244  documentation.
244  </P>  </P>
245  <br><a name="SEC3" href="#TOC1">NEWLINES</a><br>  <br><a name="SEC3" href="#TOC1">NEWLINES</a><br>
246  <P>  <P>
247  PCRE supports three different conventions for indicating line breaks in  PCRE supports four different conventions for indicating line breaks in
248  strings: a single CR character, a single LF character, or the two-character  strings: a single CR (carriage return) character, a single LF (linefeed)
249  sequence CRLF. All three are used as "standard" by different operating systems.  character, the two-character sequence CRLF, or any Unicode newline sequence.
250  When PCRE is built, a default can be specified. The default default is LF,  The Unicode newline sequences are the three just mentioned, plus the single
251  which is the Unix standard. When PCRE is run, the default can be overridden,  characters VT (vertical tab, U+000B), FF (formfeed, U+000C), NEL (next line,
252  either when a pattern is compiled, or when it is matched.  U+0085), LS (line separator, U+2028), and PS (paragraph separator, U+2029).
253  <br>  </P>
254  <br>  <P>
255    Each of the first three conventions is used by at least one operating system as
256    its standard newline sequence. When PCRE is built, a default can be specified.
257    The default default is LF, which is the Unix standard. When PCRE is run, the
258    default can be overridden, either when a pattern is compiled, or when it is
259    matched.
260    </P>
261    <P>
262  In the PCRE documentation the word "newline" is used to mean "the character or  In the PCRE documentation the word "newline" is used to mean "the character or
263  pair of characters that indicate a line break".  pair of characters that indicate a line break". The choice of newline
264    convention affects the handling of the dot, circumflex, and dollar
265    metacharacters, the handling of #-comments in /x mode, and, when CRLF is a
266    recognized line ending sequence, the match position advancement for a
267    non-anchored pattern. The choice of newline convention does not affect the
268    interpretation of the \n or \r escape sequences.
269  </P>  </P>
270  <br><a name="SEC4" href="#TOC1">MULTITHREADING</a><br>  <br><a name="SEC4" href="#TOC1">MULTITHREADING</a><br>
271  <P>  <P>
# Line 301  properties is available; otherwise it is Line 314  properties is available; otherwise it is
314    PCRE_CONFIG_NEWLINE    PCRE_CONFIG_NEWLINE
315  </pre>  </pre>
316  The output is an integer whose value specifies the default character sequence  The output is an integer whose value specifies the default character sequence
317  that is recognized as meaning "newline". The three values that are supported  that is recognized as meaning "newline". The four values that are supported
318  are: 10 for LF, 13 for CR, and 3338 for CRLF. The default should normally be  are: 10 for LF, 13 for CR, 3338 for CRLF, and -1 for ANY. The default should
319  the standard sequence for your operating system.  normally be the standard sequence for your operating system.
320  <pre>  <pre>
321    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
322  </pre>  </pre>
# Line 374  fully relocatable, because it may contai Line 387  fully relocatable, because it may contai
387  argument, which is an address (see below).  argument, which is an address (see below).
388  </P>  </P>
389  <P>  <P>
390  The <i>options</i> argument contains independent bits that affect the  The <i>options</i> argument contains various bit settings that affect the
391  compilation. It should be zero if no options are required. The available  compilation. It should be zero if no options are required. The available
392  options are described below. Some of them, in particular, those that are  options are described below. Some of them, in particular, those that are
393  compatible with Perl, can also be set and unset from within the pattern (see  compatible with Perl, can also be set and unset from within the pattern (see
# Line 467  If this bit is set, a dot metacharater i Line 480  If this bit is set, a dot metacharater i
480  including those that indicate newline. Without it, a dot does not match when  including those that indicate newline. Without it, a dot does not match when
481  the current position is at a newline. This option is equivalent to Perl's /s  the current position is at a newline. This option is equivalent to Perl's /s
482  option, and it can be changed within a pattern by a (?s) option setting. A  option, and it can be changed within a pattern by a (?s) option setting. A
483  negative class such as [^a] always matches newlines, independent of the setting  negative class such as [^a] always matches newline characters, independent of
484  of this option.  the setting of this option.
485  <pre>  <pre>
486    PCRE_DUPNAMES    PCRE_DUPNAMES
487  </pre>  </pre>
# Line 531  occurrences of ^ or $ in a pattern, sett Line 544  occurrences of ^ or $ in a pattern, sett
544    PCRE_NEWLINE_CR    PCRE_NEWLINE_CR
545    PCRE_NEWLINE_LF    PCRE_NEWLINE_LF
546    PCRE_NEWLINE_CRLF    PCRE_NEWLINE_CRLF
547      PCRE_NEWLINE_ANY
548  </pre>  </pre>
549  These options override the default newline definition that was chosen when PCRE  These options override the default newline definition that was chosen when PCRE
550  was built. Setting the first or the second specifies that a newline is  was built. Setting the first or the second specifies that a newline is
551  indicated by a single character (CR or LF, respectively). Setting both of them  indicated by a single character (CR or LF, respectively). Setting
552  specifies that a newline is indicated by the two-character CRLF sequence. For  PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character
553  convenience, PCRE_NEWLINE_CRLF is defined to contain both bits. The only time  CRLF sequence. Setting PCRE_NEWLINE_ANY specifies that any Unicode newline
554  that a line break is relevant when compiling a pattern is if PCRE_EXTENDED is  sequence should be recognized. The Unicode newline sequences are the three just
555  set, and an unescaped # outside a character class is encountered. This  mentioned, plus the single characters VT (vertical tab, U+000B), FF (formfeed,
556  indicates a comment that lasts until after the next newline.  U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
557    (paragraph separator, U+2029). The last two are recognized only in UTF-8 mode.
558    </P>
559    <P>
560    The newline setting in the options word uses three bits that are treated
561    as a number, giving eight possibilities. Currently only five are used (default
562    plus the four values above). This means that if you set more than one newline
563    option, the combination may or may not be sensible. For example,
564    PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but
565    other combinations yield unused numbers and cause an error.
566    </P>
567    <P>
568    The only time that a line break is specially recognized when compiling a
569    pattern is if PCRE_EXTENDED is set, and an unescaped # outside a character
570    class is encountered. This indicates a comment that lasts until after the next
571    line break sequence. In other circumstances, line break sequences are treated
572    as literal data, except that in PCRE_EXTENDED mode, both CR and LF are treated
573    as whitespace characters and are therefore ignored.
574  </P>  </P>
575  <P>  <P>
576  The newline option set at compile time becomes the default that is used for  The newline option that is set at compile time becomes the default that is used
577  <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b>, but it can be overridden.  for <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b>, but it can be overridden.
578  <pre>  <pre>
579    PCRE_NO_AUTO_CAPTURE    PCRE_NO_AUTO_CAPTURE
580  </pre>  </pre>
# Line 587  strings. Line 618  strings.
618  <P>  <P>
619  The following table lists the error codes than may be returned by  The following table lists the error codes than may be returned by
620  <b>pcre_compile2()</b>, along with the error messages that may be returned by  <b>pcre_compile2()</b>, along with the error messages that may be returned by
621  both compiling functions.  both compiling functions. As PCRE has developed, some error codes have fallen
622    out of use. To avoid confusion, they have not been re-used.
623  <pre>  <pre>
624     0  no error     0  no error
625     1  \ at end of pattern     1  \ at end of pattern
# Line 599  both compiling functions. Line 631  both compiling functions.
631     7  invalid escape sequence in character class     7  invalid escape sequence in character class
632     8  range out of order in character class     8  range out of order in character class
633     9  nothing to repeat     9  nothing to repeat
634    10  operand of unlimited repeat could match the empty string    10  [this code is not in use]
635    11  internal error: unexpected repeat    11  internal error: unexpected repeat
636    12  unrecognized character after (?    12  unrecognized character after (?
637    13  POSIX named classes are supported only within a class    13  POSIX named classes are supported only within a class
# Line 608  both compiling functions. Line 640  both compiling functions.
640    16  erroffset passed as NULL    16  erroffset passed as NULL
641    17  unknown option bit(s) set    17  unknown option bit(s) set
642    18  missing ) after comment    18  missing ) after comment
643    19  parentheses nested too deeply    19  [this code is not in use]
644    20  regular expression too large    20  regular expression too large
645    21  failed to get memory    21  failed to get memory
646    22  unmatched parentheses    22  unmatched parentheses
# Line 622  both compiling functions. Line 654  both compiling functions.
654    30  unknown POSIX class name    30  unknown POSIX class name
655    31  POSIX collating elements are not supported    31  POSIX collating elements are not supported
656    32  this version of PCRE is not compiled with PCRE_UTF8 support    32  this version of PCRE is not compiled with PCRE_UTF8 support
657    33  spare error    33  [this code is not in use]
658    34  character value in \x{...} sequence is too large    34  character value in \x{...} sequence is too large
659    35  invalid condition (?(0)    35  invalid condition (?(0)
660    36  \C not allowed in lookbehind assertion    36  \C not allowed in lookbehind assertion
# Line 631  both compiling functions. Line 663  both compiling functions.
663    39  closing ) for (?C expected    39  closing ) for (?C expected
664    40  recursive call could loop indefinitely    40  recursive call could loop indefinitely
665    41  unrecognized character after (?P    41  unrecognized character after (?P
666    42  syntax error after (?P    42  syntax error in subpattern name (missing terminator)
667    43  two named subpatterns have the same name    43  two named subpatterns have the same name
668    44  invalid UTF-8 string    44  invalid UTF-8 string
669    45  support for \P, \p, and \X has not been compiled    45  support for \P, \p, and \X has not been compiled
# Line 641  both compiling functions. Line 673  both compiling functions.
673    49  too many named subpatterns (maximum 10,000)    49  too many named subpatterns (maximum 10,000)
674    50  repeated subpattern is too long    50  repeated subpattern is too long
675    51  octal value is greater than \377 (not in UTF-8 mode)    51  octal value is greater than \377 (not in UTF-8 mode)
676      52  internal error: overran compiling workspace
677      53  internal error: previously-checked referenced subpattern not found
678      54  DEFINE group contains more than one branch
679      55  repeating a DEFINE group is not allowed
680      56  inconsistent NEWLINE options"
681  </PRE>  </PRE>
682  </P>  </P>
683  <br><a name="SEC9" href="#TOC1">STUDYING A PATTERN</a><br>  <br><a name="SEC9" href="#TOC1">STUDYING A PATTERN</a><br>
# Line 810  still recognized for backwards compatibi Line 847  still recognized for backwards compatibi
847  </P>  </P>
848  <P>  <P>
849  If there is a fixed first byte, for example, from a pattern such as  If there is a fixed first byte, for example, from a pattern such as
850  (cat|cow|coyote). Otherwise, if either  (cat|cow|coyote), its value is returned. Otherwise, if either
851  <br>  <br>
852  <br>  <br>
853  (a) the pattern was compiled with the PCRE_MULTILINE option, and every branch  (a) the pattern was compiled with the PCRE_MULTILINE option, and every branch
# Line 868  alphabetical order. When PCRE_DUPNAMES i Line 905  alphabetical order. When PCRE_DUPNAMES i
905  their parentheses numbers. For example, consider the following pattern (assume  their parentheses numbers. For example, consider the following pattern (assume
906  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  PCRE_EXTENDED is set, so white space - including newlines - is ignored):
907  <pre>  <pre>
908    (?P&#60;date&#62; (?P&#60;year&#62;(\d\d)?\d\d) - (?P&#60;month&#62;\d\d) - (?P&#60;day&#62;\d\d) )    (?&#60;date&#62; (?&#60;year&#62;(\d\d)?\d\d) - (?&#60;month&#62;\d\d) - (?&#60;day&#62;\d\d) )
909  </pre>  </pre>
910  There are four named subpatterns, so the table has four entries, and each entry  There are four named subpatterns, so the table has four entries, and each entry
911  in the table is eight bytes long. The table is as follows, with non-printing  in the table is eight bytes long. The table is as follows, with non-printing
# Line 1116  matching time. Line 1153  matching time.
1153    PCRE_NEWLINE_CR    PCRE_NEWLINE_CR
1154    PCRE_NEWLINE_LF    PCRE_NEWLINE_LF
1155    PCRE_NEWLINE_CRLF    PCRE_NEWLINE_CRLF
1156      PCRE_NEWLINE_ANY
1157  </pre>  </pre>
1158  These options override the newline definition that was chosen or defaulted when  These options override the newline definition that was chosen or defaulted when
1159  the pattern was compiled. For details, see the description <b>pcre_compile()</b>  the pattern was compiled. For details, see the description of
1160  above. During matching, the newline choice affects the behaviour of the dot,  <b>pcre_compile()</b> above. During matching, the newline choice affects the
1161  circumflex, and dollar metacharacters.  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1162    the way the match position is advanced after a match failure for an unanchored
1163    pattern. When PCRE_NEWLINE_CRLF or PCRE_NEWLINE_ANY is set, and a match attempt
1164    fails when the current position is at a CRLF sequence, the match position is
1165    advanced by two characters instead of one, in other words, to after the CRLF.
1166  <pre>  <pre>
1167    PCRE_NOTBOL    PCRE_NOTBOL
1168  </pre>  </pre>
# Line 1334  compiled in an environment of one endian Line 1376  compiled in an environment of one endian
1376  other endianness. This is the error that PCRE gives when the magic number is  other endianness. This is the error that PCRE gives when the magic number is
1377  not present.  not present.
1378  <pre>  <pre>
1379    PCRE_ERROR_UNKNOWN_NODE   (-5)    PCRE_ERROR_UNKNOWN_OPCODE (-5)
1380  </pre>  </pre>
1381  While running the pattern match, an unknown item was encountered in the  While running the pattern match, an unknown item was encountered in the
1382  compiled pattern. This error could be caused by a bug in PCRE or by overwriting  compiled pattern. This error could be caused by a bug in PCRE or by overwriting
# Line 1360  The backtracking limit, as specified by Line 1402  The backtracking limit, as specified by
1402  <b>pcre_extra</b> structure (or defaulted) was reached. See the description  <b>pcre_extra</b> structure (or defaulted) was reached. See the description
1403  above.  above.
1404  <pre>  <pre>
   PCRE_ERROR_RECURSIONLIMIT (-21)  
 </pre>  
 The internal recursion limit, as specified by the <i>match_limit_recursion</i>  
 field in a <b>pcre_extra</b> structure (or defaulted) was reached. See the  
 description above.  
 <pre>  
1405    PCRE_ERROR_CALLOUT        (-9)    PCRE_ERROR_CALLOUT        (-9)
1406  </pre>  </pre>
1407  This error is never generated by <b>pcre_exec()</b> itself. It is provided for  This error is never generated by <b>pcre_exec()</b> itself. It is provided for
# Line 1403  in PCRE or by overwriting of the compile Line 1439  in PCRE or by overwriting of the compile
1439    PCRE_ERROR_BADCOUNT       (-15)    PCRE_ERROR_BADCOUNT       (-15)
1440  </pre>  </pre>
1441  This error is given if the value of the <i>ovecsize</i> argument is negative.  This error is given if the value of the <i>ovecsize</i> argument is negative.
1442    <pre>
1443      PCRE_ERROR_RECURSIONLIMIT (-21)
1444    </pre>
1445    The internal recursion limit, as specified by the <i>match_limit_recursion</i>
1446    field in a <b>pcre_extra</b> structure (or defaulted) was reached. See the
1447    description above.
1448    <pre>
1449      PCRE_ERROR_NULLWSLIMIT    (-22)
1450    </pre>
1451    When a group that can match an empty substring is repeated with an unbounded
1452    upper limit, the subject position at the start of the group must be remembered,
1453    so that a test for an empty string can be made when the end of the group is
1454    reached. Some workspace is required for this; if it runs out, this error is
1455    given.
1456    <pre>
1457      PCRE_ERROR_BADNEWLINE     (-23)
1458    </pre>
1459    An invalid combination of PCRE_NEWLINE_<i>xxx</i> options was given.
1460    </P>
1461    <P>
1462    Error numbers -16 to -20 are not used by <b>pcre_exec()</b>.
1463  </P>  </P>
1464  <br><a name="SEC15" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a><br>  <br><a name="SEC15" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a><br>
1465  <P>  <P>
# Line 1457  the string is placed in buffer, w Line 1514  the string is placed in buffer, w
1514  <i>buffersize</i>, while for <b>pcre_get_substring()</b> a new block of memory is  <i>buffersize</i>, while for <b>pcre_get_substring()</b> a new block of memory is
1515  obtained via <b>pcre_malloc</b>, and its address is returned via  obtained via <b>pcre_malloc</b>, and its address is returned via
1516  <i>stringptr</i>. The yield of the function is the length of the string, not  <i>stringptr</i>. The yield of the function is the length of the string, not
1517  including the terminating zero, or one of  including the terminating zero, or one of these error codes:
1518  <pre>  <pre>
1519    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1520  </pre>  </pre>
# Line 1474  and builds a list of pointers to them. A Line 1531  and builds a list of pointers to them. A
1531  memory that is obtained via <b>pcre_malloc</b>. The address of the memory block  memory that is obtained via <b>pcre_malloc</b>. The address of the memory block
1532  is returned via <i>listptr</i>, which is also the start of the list of string  is returned via <i>listptr</i>, which is also the start of the list of string
1533  pointers. The end of the list is marked by a NULL pointer. The yield of the  pointers. The end of the list is marked by a NULL pointer. The yield of the
1534  function is zero if all went well, or  function is zero if all went well, or the error code
1535  <pre>  <pre>
1536    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1537  </pre>  </pre>
# Line 1520  provided. Line 1577  provided.
1577  To extract a substring by name, you first have to find associated number.  To extract a substring by name, you first have to find associated number.
1578  For example, for this pattern  For example, for this pattern
1579  <pre>  <pre>
1580    (a+)b(?P&#60;xxx&#62;\d+)...    (a+)b(?&#60;xxx&#62;\d+)...
1581  </pre>  </pre>
1582  the number of the subpattern called "xxx" is 2. If the name is known to be  the number of the subpattern called "xxx" is 2. If the name is known to be
1583  unique (PCRE_DUPNAMES was not set), you can find the number from the name by  unique (PCRE_DUPNAMES was not set), you can find the number from the name by
# Line 1575  argument is the compiled pattern, and th Line 1632  argument is the compiled pattern, and th
1632  fourth are pointers to variables which are updated by the function. After it  fourth are pointers to variables which are updated by the function. After it
1633  has run, they point to the first and last entries in the name-to-number table  has run, they point to the first and last entries in the name-to-number table
1634  for the given name. The function itself returns the length of each entry, or  for the given name. The function itself returns the length of each entry, or
1635  PCRE_ERROR_NOSUBSTRING if there are none. The format of the table is described  PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is
1636  above in the section entitled <i>Information about a pattern</i>. Given all the  described above in the section entitled <i>Information about a pattern</i>.
1637  relevant entries for the name, you can extract each of their numbers, and hence  Given all the relevant entries for the name, you can extract each of their
1638  the captured data, if any.  numbers, and hence the captured data, if any.
1639  </P>  </P>
1640  <br><a name="SEC18" href="#TOC1">FINDING ALL POSSIBLE MATCHES</a><br>  <br><a name="SEC18" href="#TOC1">FINDING ALL POSSIBLE MATCHES</a><br>
1641  <P>  <P>
# Line 1608  will yield PCRE_ERROR_NOMATCH. Line 1665  will yield PCRE_ERROR_NOMATCH.
1665  </P>  </P>
1666  <P>  <P>
1667  The function <b>pcre_dfa_exec()</b> is called to match a subject string against  The function <b>pcre_dfa_exec()</b> is called to match a subject string against
1668  a compiled pattern, using a "DFA" matching algorithm. This has different  a compiled pattern, using a matching algorithm that scans the subject string
1669  characteristics to the normal algorithm, and is not compatible with Perl. Some  just once, and does not backtrack. This has different characteristics to the
1670  of the features of PCRE patterns are not supported. Nevertheless, there are  normal algorithm, and is not compatible with Perl. Some of the features of PCRE
1671  times when this kind of matching can be useful. For a discussion of the two  patterns are not supported. Nevertheless, there are times when this kind of
1672  matching algorithms, see the  matching can be useful. For a discussion of the two matching algorithms, see
1673    the
1674  <a href="pcrematching.html"><b>pcrematching</b></a>  <a href="pcrematching.html"><b>pcrematching</b></a>
1675  documentation.  documentation.
1676  </P>  </P>
# Line 1671  matching string. Line 1729  matching string.
1729    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
1730  </pre>  </pre>
1731  Setting the PCRE_DFA_SHORTEST option causes the matching algorithm to stop as  Setting the PCRE_DFA_SHORTEST option causes the matching algorithm to stop as
1732  soon as it has found one match. Because of the way the DFA algorithm works,  soon as it has found one match. Because of the way the alternative algorithm
1733  this is necessarily the shortest possible match at the first possible matching  works, this is necessarily the shortest possible match at the first possible
1734  point in the subject string.  matching point in the subject string.
1735  <pre>  <pre>
1736    PCRE_DFA_RESTART    PCRE_DFA_RESTART
1737  </pre>  </pre>
# Line 1711  the three matched strings are Line 1769  the three matched strings are
1769  On success, the yield of the function is a number greater than zero, which is  On success, the yield of the function is a number greater than zero, which is
1770  the number of matched substrings. The substrings themselves are returned in  the number of matched substrings. The substrings themselves are returned in
1771  <i>ovector</i>. Each string uses two elements; the first is the offset to the  <i>ovector</i>. Each string uses two elements; the first is the offset to the
1772  start, and the second is the offset to the end. All the strings have the same  start, and the second is the offset to the end. In fact, all the strings have
1773  start offset. (Space could have been saved by giving this only once, but it was  the same start offset. (Space could have been saved by giving this only once,
1774  decided to retain some compatibility with the way <b>pcre_exec()</b> returns  but it was decided to retain some compatibility with the way <b>pcre_exec()</b>
1775  data, even though the meaning of the strings is different.)  returns data, even though the meaning of the strings is different.)
1776  </P>  </P>
1777  <P>  <P>
1778  The strings are returned in reverse order of length; that is, the longest  The strings are returned in reverse order of length; that is, the longest
# Line 1740  that it does not support, for instance, Line 1798  that it does not support, for instance,
1798  <pre>  <pre>
1799    PCRE_ERROR_DFA_UCOND      (-17)    PCRE_ERROR_DFA_UCOND      (-17)
1800  </pre>  </pre>
1801  This return is given if <b>pcre_dfa_exec()</b> encounters a condition item in a  This return is given if <b>pcre_dfa_exec()</b> encounters a condition item that
1802  pattern that uses a back reference for the condition. This is not supported.  uses a back reference for the condition, or a test for recursion in a specific
1803    group. These are not supported.
1804  <pre>  <pre>
1805    PCRE_ERROR_DFA_UMLIMIT    (-18)    PCRE_ERROR_DFA_UMLIMIT    (-18)
1806  </pre>  </pre>
# Line 1761  recursively, using private vectors for < Line 1820  recursively, using private vectors for <
1820  error is given if the output vector is not large enough. This should be  error is given if the output vector is not large enough. This should be
1821  extremely rare, as a vector of size 1000 is used.  extremely rare, as a vector of size 1000 is used.
1822  </P>  </P>
1823    <br><a name="SEC20" href="#TOC1">SEE ALSO</a><br>
1824    <P>
1825    <b>pcrebuild</b>(3), <b>pcrecallout</b>(3), <b>pcrecpp(3)</b>(3),
1826    <b>pcrematching</b>(3), <b>pcrepartial</b>(3), <b>pcreposix</b>(3),
1827    <b>pcreprecompile</b>(3), <b>pcresample</b>(3), <b>pcrestack</b>(3).
1828    </P>
1829  <P>  <P>
1830  Last updated: 08 June 2006  Last updated: 30 November 2006
1831  <br>  <br>
1832  Copyright &copy; 1997-2006 University of Cambridge.  Copyright &copy; 1997-2006 University of Cambridge.
1833  <p>  <p>
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